CN115103868A

CN115103868A - Process for preparing polyesters with recycled components

Info

Publication number: CN115103868A
Application number: CN202080097158.9A
Authority: CN
Inventors: E·E·小豪厄尔; M·P·埃卡特; T·W·基弗; B·N·杰克; J·M·霍尔顿; D·L·马丁
Original assignee: Eastman Chemical Co
Current assignee: Eastman Chemical Co
Priority date: 2019-12-19
Filing date: 2020-12-16
Publication date: 2022-09-23
Also published as: BR112022011787A2; MX2022007257A; JP2023506950A; EP4077468A1; CA3162305A1; KR20220119656A; US20230026172A1; WO2021126938A1

Abstract

In various aspects, a process for preparing a polyester having recycled content is described. The process of the present disclosure efficiently and cost-effectively introduces recycled DMT into existing TPA-based polyester production systems. Recycled feed compositions for making polyesters with recycled components and recycled component polyesters are also described.

Description

Process for preparing polyesters with recycled content

Technical Field

The present disclosure relates generally to the field of polyester recycling and polyester production, and more particularly to polyester production processes that include the use of methanolysis reaction products in forming polyesters with recycled components.

Background

Polyester is one of the most purchased and utilized diverse classes of polymers in the world, with recently reported published world yields (including recycling) well in excess of 75 million tons. This level of commercial success may be attributable in part to an attractive combination of relative cost, manufacturability, and competitive performance attributes of polyesters. The physical, chemical, and thermal properties of polyesters make them useful and desirable for a wide variety of end-use applications. Polyethylene terephthalate (PET) is one of the most common types of polyesters used in many end uses. With the continued commercial success of polyesters in general and PET in particular, efforts have been made to recover materials from post-consumer, post-industrial, waste and other sources and reuse these materials as a replacement for basic processing methods such as landfills.

In one known recycling process, recycled PET is blended with virgin material. This process has been used, for example, to prepare blends of virgin poly (butylene terephthalate) ("PBT") with recycled PET to obtain PBT-based products with recycled ingredients (see, e.g., U.S. patent publication No. 2009/0275698). However, such blends can often be immiscible and result in a relatively opaque material. Blending is therefore not a consistently satisfactory process that provides a commercially valuable end product with recycled ingredients.

In another recycling process, the polyester is depolymerized to form the monomer units originally used for its preparation. One commercially used process for depolymerization of polyesters is methanolysis. In methanolysis, a polyester is reacted with methanol to produce a depolymerized polyester mixture comprising a polyester oligomer, dimethyl terephthalate ("DMT"), and ethylene glycol ("EG"). Depending on the composition of the polyester in the methanolysis feed stream, other monomers may also be prepared, such as, for example, 1, 4-cyclohexanedimethanol ("CHDM") and diethylene glycol. Some representative methods of methanolysis of PET are described in u.s. pat. nos. 3,037,050; 3,321,510; 3,776,945, respectively; 5,051,528, respectively; 5,298,530, respectively; 5,414,022, respectively; 5,432,203, respectively; 5,576,456 and 6,262,294, the contents and disclosure of each of which are incorporated herein by reference. A representative methanolysis process is also described in u.s. Pat. number 5,298,530, the contents and disclosure of which are incorporated herein by reference. The' 530 patent describes a process for recovering ethylene glycol and dimethyl terephthalate from waste polyester. The process includes the steps of dissolving waste polyester in an oligomer of Ethylene Glycol (EG) and terephthalic acid (TPA) or dimethyl terephthalate (DMT) and passing superheated methanol through the mixture. The oligomers may include any low molecular weight polyester polymer having the same composition as the waste material used as the starting component, such that the waste material polymer will dissolve in the low molecular weight oligomers. Dimethyl terephthalate and ethylene glycol are recovered from the methanol vapor stream emitted from the depolymerization reactor.

With the goal of producing and selling new materials with recycled components, manufacturers are continually investigating the use of monomer units, particularly DMT and EG, generated via depolymerization. For example, the assignee of the present disclosure generally teaches in U.S. published patent application No. 2013/0041053 that recycled monomers, such as DMT, can be combined with virgin monomers in the preparation of polyesters. However, the proposal has its drawbacks. First, consider the operation of an esterification/transesterification step conducted at a temperature generally in the range of from about 150 ℃ to about 250 ℃ for a period of from about 0.5 to about 8 hours and at a pressure in the range of from about 0.0 kPa gauge to about 414 kPa gauge (60 psig). Such conditions are inconsistent with the operating conditions suitable for current terephthalic acid (TPA-based) polyester production processes in which the feed is essentially free of intentionally added esters and contains only diacid, primarily terephthalic acid, and one or more diols. Thus, it would seem impracticable to achieve recycle components by introducing recycle materials such as recycle DMT (r-DMT) and/or recycle ethylene glycol (r-EG) into current TPA-based processes without operation and potentially damaging the process settings and associated product uniformity and yield. In addition, the' 053 publication indicates that when a mixed acid/ester feed is used, a 3-stage preparation procedure should be employed as described in U.S. Pat. No. 5,290,631. The additional process steps bring additional capital, manufacturing and labor costs to it.

Accordingly, there is a continuing unmet need for a process for producing polyester with recycled components by efficiently and cost-effectively introducing recycled materials, such as recycled DMT (r-DMT) and recycled ethylene glycol (r-EG), into existing TPA-based polyester production systems.

Disclosure of Invention

In a first aspect, the present disclosure relates to a process for preparing a polyester having recycled content, wherein the process comprises the steps of: feeding a recycle feed comprising an ester recycle material selected from the group consisting of r-DMT, transesterified r-DMT, and combinations thereof to the at least one reaction zone to form a reaction mixture comprising recycled components in the at least one reaction zone; reacting the reaction mixture to form a polyester oligomer mixture having recycled content; and polycondensing the recycled component oligomer mixture to form a polyester with recycled components.

In another aspect, the present disclosure relates to a recycle feed composition for making polyesters with recycle components. The recycle feed composition of the present disclosure comprises an ester recycle material selected from the group consisting of r-DMT, transesterified r-DMT, and combinations thereof; and at least one of: dimethyl isophthalate recycle material (r-DMI) and residual catalyst material selected from germanium material and antimony material and combinations thereof.

In yet another aspect, the present disclosure relates to polyesters with recycled content.

Other aspects of the present disclosure are as disclosed and claimed herein.

Detailed Description

The term "polyester" as used herein is intended to generally include, but is not limited to, homopolyesters as well as copolyesters, tercopolyesters, and the like, and is generally prepared in a general sense by reacting a diacid, ester thereof, or mixture of such acids or esters, with a difunctional hydroxyl compound, typically a diol (diol) or mixture of such diols or diols. Alternatively, the difunctional carboxylic acid may be a hydroxycarboxylic acid and the difunctional hydroxyl compound may be an aromatic nucleus bearing 2 hydroxyl substituents, such as for example hydroquinone. Of particular interest in connection with the present disclosure as described herein are polyesters that produce one or both of dimethyl terephthalate and ethylene glycol via depolymerization by methanolysis or glycolysis with subsequent reaction products methanolysis, or both.

In a first aspect, the present disclosure relates to a process for preparing a polyester having recycled content. The method of the present disclosure comprises the steps of: feeding a recycle feed comprising an ester recycle material selected from the group consisting of r-DMT, transesterified r-DMT, and combinations thereof to the at least one reaction zone to form a reaction mixture comprising recycled components in the at least one reaction zone; reacting the reaction mixture to form a polyester oligomer mixture having recycled content; and polycondensing the recycled component oligomer mixture to form a polyester with recycled components.

In one or more embodiments, the reacting step comprises reacting the reaction mixture at a temperature of at least 250 ℃ for a total average residence time of from 30 minutes to 12 hours, or from 1 hour to 10 hours, or from 1 hour to 8 hours. In one or more embodiments, the reacting step comprises reacting the reaction mixture at a temperature of 250 ℃ to 350 ℃, or 250 ℃ to 300 ℃, or 260 ℃ to 300 ℃, or 250 ℃ to 275 ℃.

As mentioned above, polyesters may be prepared in a general sense by reacting a diacid, ester thereof, or mixture of such acids or esters with a difunctional hydroxyl compound, typically a diol or mixture of such diols or diols. Thus, one of ordinary skill will appreciate that, in order to form the disclosed polyesters with recycled components, the reaction mixture in at least one reaction zone comprises components known in the art for forming polyesters, such as (i) diacids, esters thereof, or mixtures of such acids or esters and (ii) difunctional hydroxyl compounds, such as diols or glycols, or mixtures of such diols or glycols. In one or more embodiments, the reaction mixture includes a recycle component. In one or more embodiments, the reaction mixture includes a recycle component and a virgin component. As used herein, the term "recycle" is intended to mean by recycling, for example, a source of waste, off-spec, waste, post-consumer, or post-industrial material. As used herein, the term "virgin" is intended to mean prepared from raw materials, such as fossil fuel-based or bio-based raw materials, as opposed to by recycling, for example, waste, off-spec, waste, post-consumer, or post-industrial sources of materials.

In one or more embodiments, the feeding step of the process of the present disclosure further comprises feeding a glycol recycle material selected from r-EG, recycled diethylene glycol (r-DEG), and combinations thereof, to the at least one reaction zone.

In one or more embodiments, the recycle feed further comprises dimethyl isophthalate recycle material (r-DMI). In one or more embodiments, the r-DMI is present in the recycle feed in an amount of 2000 ppm or more, or 1500 ppm or more, or 1000 ppm or more, or 500 ppm or more. In one or more embodiments, the recycle feed can further comprise a terephthalic acid recycle material (r-TPA), which can include r-TPA formed via hydrolysis of r-DMT. In one or more embodiments, the process may include hydrolyzing at least some of the r-DMT to form r-TPA prior to the reacting step.

In one or more embodiments, the recycle feed also comprises residual catalyst material. The residual catalyst material may be one or more materials or compounds present in the recycle feed, the source of which is the original polyester that underwent depolymerization to form r-DMT. In one or more embodiments, the residual catalyst material may be selected from germanium materials and antimony materials and combinations thereof. In one or more embodiments, the antimony material is present in the recycle feed in an amount of from 5 to 500 ppm or from 10 to 500 ppm or from 20 to 500 ppm or 5 or more ppm. In one or more embodiments, the germanium material is present in the recycle feed in an amount of from 5 to 500 ppm or from 10 to 500 ppm or from 20 to 500 ppm or 5 or more ppm.

In one or more embodiments, the recycle feed further comprises dimethyl isophthalate recycle material (r-DMI) and residual catalyst material selected from germanium material and antimony material, and combinations thereof.

In one or more embodiments, the feeding step of the process of the present disclosure further comprises feeding the raw feed to at least one reaction zone. In one or more embodiments, at least one glycol of the primary feed is a primary glycol. The virgin feed may comprise one or more other virgin materials, such as, for example, virgin diacids, virgin diesters, virgin branching agents, such as, for example, trimellitic anhydride, and the like.

In one or more embodiments, the virgin feed is substantially free of virgin diester components. In one or more embodiments, the raw feed is substantially free of raw diacid components. Thus, in one or more embodiments, the reaction mixture may include a native diol component, or may be substantially free of a native diacid component, or may be substantially free of a native diester component. As used herein, the phrase "substantially free of is generally intended to mean that the raw feed does not contain any intentionally added raw acid and/or ester components. However, one of ordinary skill will appreciate that incidental diacid/diol reactions in the primary feed may result in the formation of small amounts of primary diester compounds. Thus, in one or more embodiments, the phrase "substantially free of" in describing the native diester component of the native feed is intended to mean that the native feed comprises (based on the total moles of diacid + diester in the native feed) no greater than 5 mole% or no greater than 4 mole% or no greater than 3 mole% or no greater than 2 mole% or no greater than 1 mole% of the native diester compound. In one or more embodiments, the reaction mixture may comprise at least 95 wt.%, or at least 96 wt.%, or at least 97 wt.%, or at least 98 wt.%, or at least 99 wt.%, or 100 wt.% of the recycle feed, based on the total weight of the reaction mixture.

In one or more embodiments of this aspect, the step of feeding the raw feed to the reaction zone precedes the step of feeding the recycled feed. In one or more embodiments of this aspect, the process further comprises the step of reacting at least some of the virgin feed in the reaction zone to form virgin polyester oligomers prior to or simultaneously with the step of feeding recycle feed.

In one or more embodiments, the ester recycle material of the feeding step is added in an amount sufficient to constitute 1 to 100 mole percent or 25% to 100% or 90% to 100% or 1% to 50%, or based on the total moles of 1, 4-dicarboxybenzene equivalents of diacid in the polyester with recycled components. It will be appreciated that the relative amounts of r-DMT and diacid components (if any is present in the polyester primary feed stream) in the reaction mixture will affect the type, structure, and overall recycle composition of the particular polyester formed by the process of the present disclosure.

In one or more embodiments, the step of feeding the raw feed to the reaction zone begins after the step of feeding the ester recycle material to the reactor. In one or more embodiments, the step of feeding the raw feed to the reaction zone and the step of feeding the recycled feed to the reaction zone begin at the same time or at the same physical location. Although the present disclosure is generally described above in terms of the step of feeding the recycle feed and, in some embodiments, the step of feeding the raw feed to the reaction zone to form the reaction mixture, it will be understood that the number and composition of the individual feed streams of feed material need not be limited. As a non-limiting example, the process may include combining the recycle feed and the native feed to form a combined recycle/native feed, and feeding the combined recycle/native feed to at least one reaction zone to form the reaction mixture.

In some typical TPA-based polyester production processes, the primary acid component can be terephthalic acid, optionally with an amount of isophthalic acid that is lower than the amount of terephthalic acid. Thus, in one or more embodiments, the raw feed includes a raw diacid component. In one or more embodiments, the virgin feed comprises one or both of virgin terephthalic acid and virgin isophthalic acid. In one or more embodiments, the virgin diacid component of the virgin feed comprises at least 90 mole percent, or at least 92 mole percent, or at least 94 mole percent, or at least 95 mole percent, or at least 96 mole percent, or at least 98 mole percent virgin terephthalic acid, based on the total moles of diacid in the virgin feed. In one or more embodiments, the raw feed comprises no greater than 10 mole percent, or no greater than 5 mole percent, of raw isophthalic acid, based on the total moles of acid in the raw feed. In one or more embodiments, the diacid component of the raw feed comprises 100 mole percent terephthalic acid, based on the total moles of acid in the raw feed.

The process for the preparation of TPA based polyesters can be used to produce copolyesters having two or more diol residues. Thus, in one or more embodiments, the native feed comprises one or more native glycols. Suitable diols are well known in the art, and non-limiting examples include ethylene glycol, 1, 3-propanediol, 1, 4-butanediol, 1, 5-pentanediol, 1, 6-hexanediol, 1, 7-heptanediol, 1, 8-octanediol, 1, 10-decanediol, diethylene glycol, triethylene glycol, polyethylene glycol, polytetrahydrofuran, polyoxymethylene, isosorbide, 1, 3-and 1, 4-Cyclohexanedimethanol (CHDM), 1, 4-cyclohexanedimethanol, 2,4, 4-tetraalkylcyclobutanediol, including 2,2,4, 4-Tetramethylcyclobutanediol (TMCD), neopentyl glycol, 2, 4-trimethyl-1, 3-pentanediol, glycerol, trimethylolpropane, pentaerythritol (pentaerythritol), resorcinol, glycerol, trimethylolpropane, and mixtures thereof, Hydroquinone and catechol, and isomers and combinations thereof. In one or more embodiments, the native glycol component of the native feed includes one or more glycols selected from the group consisting of: ethylene glycol, diethylene glycol, neopentyl glycol, 2,4, 4-tetramethyl-1, 3-cyclobutanediol (TMCD), Cyclohexanedimethanol (CHDM), isomers thereof, and combinations thereof.

The ester recycle material of the feed step is selected from the group consisting of recycled dimethyl terephthalate (r-DMT), transesterified r-DMT, and combinations thereof. Transesterified r-DMT as used herein is intended to include r-DMT that has been transesterified with one or more alcohols, such as glycols, such that the methyl ester functionality of the r-DMT is replaced by an ester functionality formed from the one or more alcohols. Thus, in one or more embodiments, the methods of the present disclosure include a step of pre-reacting at least some r-DMT with one or more alcohols to form a transesterified r-DMT prior to the feeding step. In one or more embodiments, the alcohol is a diol selected from the group consisting of: ethylene glycol, 1, 3-propanediol, 1, 4-butanediol, 1, 5-pentanediol, 1, 6-hexanediol, 1, 7-heptanediol, 1, 8-octanediol, 1, 10-decanediol, diethylene glycol, triethylene glycol, polyethylene glycol, polytetrahydrofuran, polyoxymethylene, isosorbide, 1, 3-and 1, 4-Cyclohexanedimethanol (CHDM), 1, 4-cyclohexanedimethanol, 2,4, 4-tetraalkylcyclobutanediol, including 2,2,4, 4-Tetramethylcyclobutanediol (TMCD), neopentyl glycol, 2, 4-trimethyl-1, 3-pentanediol, glycerol, trimethylolpropane, pentaerythritol, resorcinol, hydroquinone, and catechol, and isomers and combinations thereof. In one or more embodiments, the alcohol is a diol selected from the group consisting of ethylene glycol, diethylene glycol, neopentyl glycol, 2,4, 4-tetramethyl-1, 3-cyclobutanediol, cyclohexanedimethanol, ethylene glycol, 2,4, 4-tetramethyl-1, 4-cyclobutanediol, isomers thereof, and combinations thereof. In one or more embodiments, the pre-reaction step is carried out in the presence of a metal-based catalyst. Non-limiting examples of metals of the metal-based catalyst include Sb, Ti, Sn, Mo, Ge, Zn, Co, Mn, Cd, Al, Li, Pb, Mg, Ca, Ag, Na, Ce, Ba, Hg, Fe, Cu, and combinations thereof. In one or more embodiments, the metal for the metal-based catalyst is selected from the group consisting of titanium, manganese, and zinc, and combinations thereof. In one or more embodiments, the reaction conditions of the pre-reaction step will be selected to substitute the majority (greater than 50 mole%) of the methyl ester functional groups of the recycled material with glycol ester linkages (linkages) of one or more glycols from the pre-reaction step, such as, for example, 2,4, 4-tetramethyl-1, 4-cyclobutanediol ester linkages. In one or more embodiments, the one or more glycols of the pre-reaction step comprises 2,2,4, 4-tetramethyl-1, 4-cyclobutanediol and the catalyst is a tin catalyst.

One measure of the reactants in the reaction mixture is called the "molar ratio", which is the ratio of the molar amount of diol in the reaction mixture to the molar amount of the sum of diacid + ester in the reaction mixture:

MR = Md/(Ma + Me)

where MR is the molar ratio, Md is the moles of diol in the reaction mixture, Ma is the moles of acid in the reaction mixture, and Me is the moles of ester in the reaction mixture. In one or more embodiments, the molar ratio of the reaction mixture is 4 or less or 3 or less or 2.5 or less or 2 or less or 1.5 or less or 1 to 6 or 1.5 or 6 or 2 to 6 or 2.5 to 6 or 1 to 4 or 1.5 to 4 or 2 to 4.

Applicants have unexpectedly discovered that polyesters having recycled components can be efficiently and effectively produced by a process in which recycled monomers, particularly r-DMT, can be combined with other recycled or virgin materials and reacted to form polyesters having recycled components using process parameters, equipment, reaction conditions, and the like that are more typical for TPA-based production processes. Thus, in one or more embodiments, the methods of the present disclosure include reacting the reaction mixture at a temperature of at least 250 ℃ or at least 260 ℃ or at least 270 ℃ or at least 275 ℃ for a total average residence time of from 30 minutes to 12 hours. In one or more embodiments, the methods of the present disclosure include reacting the reaction mixture at a temperature of at least 250 ℃ or at least 260 ℃ or at least 270 ℃ or at least 275 ℃ for a total average residence time of 4 hours or less, 3 hours or less, 2 hours or less, or 1 hour or less.

Although the processes described herein are with respect to a single (at least one) reaction zone in which the initial reaction mixture is formed, it will be understood that multiple reaction zones may be used in series and/or multiple reactors may be used in series. In one or more embodiments, the reactor may define one or more reaction zones, while in one or more embodiments, the reaction zone may include one or more reactors. The number of reactors in the reaction zone may be 4 or less, or 3 or less, or 2 or less, or 1 or less. A reaction zone is defined as a vessel (such as a CSTR or tubular reactor), region, or zone in which the monomer reaction of the methyl or acid end groups with the diol occurs to esterify or transesterify the methyl or acid end groups. Thus, the total average residence time of a reaction step is intended to include the sum of the average residence times in all reaction zones and all reactors. The average residence time is referred to as "average" to reflect that the average residence time on a molecular basis is the average of all molecules in the reaction mixture. In one or more embodiments, the reacting step is carried out in the presence of a metal-based catalyst. Non-limiting examples of metals of the metal-based catalyst include Sb, Ti, Sn, Mo, Ge, Zn, Co, Mn, Cd, Al, Li, Pb, Mg, Ca, Ag, Na, Ce, Ba, Hg, Fe, Cu, and combinations thereof. In one or more embodiments, the metal for the metal-based catalyst is selected from the group consisting of titanium, manganese, zinc, and tin, and combinations thereof. The amount of catalyst may vary depending on a number of factors such as the reaction temperature. In one or more embodiments, the catalyst may be present in an amount of 1 to 100 ppm or 1 to 50 ppm or 1 to 40 ppm or 1 to 30 ppm or 1 to 20 ppm or 1 to 15 ppm or 1 to 10 ppm to 1 to 5 ppm or 1 to 4 ppm or 1 to 3 ppm or 1 to 2 ppm of metal based on the parts of the reaction mixture.

The reacting step of the process of the present disclosure comprises reacting the reaction mixture to form a polyester oligomer mixture having recycled components. In one or more embodiments, the recycle component oligomer mixture has a degree of polymerization of 1 to 30, or 1 to 25, or 1 to 20, or 1 to 15, and one of ordinary skill will appreciate that the degree of polymerization may increase in successive zones for embodiments that may include multiple reaction zones in series.

In one or more embodiments, the process of the present disclosure can be performed as an aspect of a waste polyester recycling process. Thus, in one or more embodiments, the process of the present disclosure further comprises, prior to the feeding step, a step of depolymerizing the waste polyester to form a depolymerized product comprising r-DMT. In one or more embodiments, the depolymerization step forms a depolymerization product comprising r-EG. The depolymerization step may form a depolymerization product stream comprising recycled dimethyl terephthalate (r-DMT) and optionally recycled ethylene glycol (r-EG). The phrase "waste polyester" as used herein is intended to include, but is not limited to, post-consumer polyester material, post-industrial polyester material, polyester waste, polyester edges (selvedge), and rejects and consumer return polyester material.

The ordinarily skilled artisan will appreciate that the depolymerization product stream may comprise a number of materials based in part on the specific composition of the waste polyester. Thus, in one or more embodiments, the depolymerization step further comprises separating r-DMT from the depolymerization product stream to form an r-DMT enriched stream.

Methods, techniques, and systems for depolymerizing polyesters are well known in the art. A particularly suitable method is methanolysis. Methanolytic depolymerization is well known in the art and is described herein above and at least in those references incorporated by reference above. The polyester recycling process is generally described in U.S. published patent application No. U.S. 2013/0041053, assigned to the assignee of the present disclosure, the contents and disclosure of which are incorporated herein by reference. The term "methanolysis" as used herein is intended to include the so-called glycolysis process, which comprises the step of forming r-DMT by a methanolysis step.

The process of the present disclosure further comprises polycondensing the recycled component oligomer mixture to form a polyester with recycled components. Polycondensation is a well-known step in the preparation of polyesters, wherein esters and ester oligomers formed by direct esterification of diacids with diols and/or transesterification of esters are polymerized by polycondensation to form polyesters, typically wherein any diols that are readily volatile under the polycondensation conditions and removed from the system are eliminated. Polycondensation can be carried out under vacuum and at a temperature generally from about 230 ℃ to about 350 ℃, preferably from about 250 ℃ to about 310 ℃, and most preferably from about 260 ℃ to about 300 ℃ for about 0.1 to about 6 hours, or preferably from about 0.2 to about 2 hours, until a polymer having the desired degree of polymerization, as determined by intrinsic viscosity, is obtained. The polymer may undergo further polymerization in the solid state.

As noted above, the recycle feed for the feed step of the process of the present disclosure may include other components such as dimethyl isophthalate recycle material (r-DMI) and/or residual catalyst material in addition to ester recycle material selected from r-DMT, transesterified r-DMT, and combinations thereof. Thus, in another aspect, the present disclosure relates to a recycle feed composition for making a polyester having recycled components. The recycle feed composition of the present disclosure comprises an ester recycle material selected from the group consisting of r-DMT, transesterified r-DMT, and combinations thereof; and at least one selected from the group consisting of: dimethyl isophthalate recycle material (r-DMI) and residual catalyst feed. In one or more embodiments, the recycle feed composition comprises dimethyl isophthalate recycle material (r-DMI). In one or more embodiments, the recycle feed composition comprises residual catalyst material. In one or more embodiments, the recycle feed composition comprises dimethyl isophthalate recycle material (r-DMI) and residual catalyst material. In one or more embodiments, the recycle feed composition comprises r-TPA, such as r-TPA formed, for example, by hydrolysis of r-DMT.

In one or more embodiments, the residual catalyst material may be selected from germanium materials and antimony materials and combinations thereof. In one or more embodiments, the r-DMI can be present in an amount of 3000 ppm or more, or 2000 ppm or more, or 1500 ppm or more, or 1000 ppm or more, based on the parts of the recycle feed composition. In one or more embodiments, residual catalyst material may be present in an amount of from 5 to 500 ppm, based on the parts of the recycle feed composition.

Applicants have also surprisingly found that the process of the present disclosure results in recycled component polyesters with unique and useful properties. Thus, in another aspect, the present disclosure relates to a polyester having a recycled component, or a recycled component polyester, wherein the number of carboxyl end groups present in the recycled component polyester is less than 25 meq/kg polymer or less than 20 meq/kg polymer or less than 15 meq/kg polymer. "carboxyl end group" refers to the free carboxyl group (-COOH) present at the end of a polyester macromolecule. The carboxyl end groups can be measured, for example, by acid-based titration with a dissolved polymer sample. In a suitable measurement technique, a weighed sample of the polyester polymer is dissolved in hot o-cresol (120) ^o +/-5 deg.C), allowed to cool, and then diluted with dichloromethane and bromocresol green indicator solution. Automatic titrator optics groundThe endpoint was determined and the results calculated.

In another aspect, the present disclosure relates to a polyester having recycled content, or a recycled content polyester, wherein the recycled content polyester has a diethylene glycol content of less than 2.0 wt.% or less than 1.8 wt.% or less than 1.6 wt.% or less than 1.5 wt.% or less than 1.4 wt.% or less than 1.2 wt.% or less than 1.0 wt.% or less than 0.8 wt.% or less than 0.6 wt.%, all based on the total weight of the polymer. "diethylene glycol content" refers to the diethylene glycol [ (HOCH) present in the recycled component polymer ₂ CH ₂ ) ₂ O ]The amount of (c). In one or more embodiments, at least some of the diethylene glycol component is an "in situ" diethylene glycol component, meaning that the diethylene glycol used to form the polymer is formed during the formation of the polymer (as opposed to being formed separately and deliberately added during the formation of the polymer). The diethylene glycol content can be measured, for example, by conventional GC techniques or proton NMR techniques after hydrolysis of the polymer.

The following examples further illustrate how the polyesters of the present disclosure can be prepared and evaluated, and are intended to be illustrative only and not limiting in scope. Unless otherwise indicated, parts are parts by weight, temperature is C (degrees celsius) or room temperature, and pressure is at or near atmospheric.

The disclosure may be further illustrated by the following examples of preferred embodiments thereof, but it will be understood that these examples are included merely for purposes of illustration and are not intended to limit the scope of the disclosure unless otherwise specifically indicated.

Examples

Example 1 oligomer Synthesis section

The oligomers used to make the high molecular weight polymer were synthesized in a 2 gallon stainless steel autoclave with a hot oil heated partial condenser. For the series of experiments shown in table 1, the reaction procedure was as follows, the starting material was charged into the reactor and sealed and heated to 260 ℃ and pressurized to 30 psig, the partial condenser was heated to 130 ℃, and once the system was at this temperature, the reaction was run for 8 hours. The reactor was then heated to the target composition and the final material was PET with 5% IPA modification and in all cases titanium tetraisopropoxide catalyst was added so that the level in the final polymer should be 15 ppm.

TABLE 1

Sample(s)	TPA (g)	IPA(g)	DMT (g)	EG(g)
					1	1894	99.7	0	1340.7
2	1420.5	99.7	553.4	1340.7
					3	947	99.7	1106.9	1340.7
4	473.5	99.7	1660.3	1340.7
					5	0	99.7	2213.8	1340.7

Then 100g of oligomer was charged to a 500 mL single neck round bottom flask. The target level of antimony catalyst was added to the flask as a glycol solution. A stainless steel stirring unit consisting of an 1/4 "diameter shaft connected to a single 2.5" diameter stirring blade was inserted into the flask, and the flask was then fitted with a glass polymer head. Attaching a polymer head consisting of a standard tapered 24/40 male adapter to the reaction flask; the side arm was positioned at approximately 45 ° to the neck of the flask to allow for volatile removal, and a portion of a glass tube through which the stirring shaft passed extended over the neck of the flask. The portion of the tube through which the stirring shaft passes is fitted with a teflon bush and rubber hose to provide a vacuum tight seal around the stirring shaft. The shaft was rotated by an 1/8 horsepower motor connected to it by a flexible "universal" joint. The side arm was connected to a vacuum system consisting of a dry ice cooled condenser and a vacuum pump. The pressure in the reaction flask was controlled by nitrogen bleed into the vacuum stream. The reaction flask was heated using a molten metal bath. All reaction parameters were monitored and controlled using a distributed data acquisition and control system. Table 2 shows the reaction sequence used by the automated control system, the phase 8 variation being used for low viscosity material production by solid stating.

TABLE 2

Number of reaction stages	Duration of the phases (minutes)	Temperature (° C)	Pressure (mm Hg)	Rate of agitation (RPM axis)
					1	0.1	265	Atmospheric pressure	1
2	25	265	Atmospheric pressure	125
					3	5	265	130	150
4	30	265	130	150
					5	10	280	4	125
6	40	280	4	125
					7	5	280	1	75
8	90 (60)	280	1	75
					9	2	280	Atmospheric pressure	0

After polymerization, each polymer was removed from the blades of the stirring shaft and ground in a hammer mill to a particle size small enough to pass through a screen perforated with 6 mm holes. All testing and solid stating was performed on the particles.

Table 3 below details examples of final IV of materials prepared with different amounts of DMT added in TPA-based processes. In Table 2,% DMT means the mole% in the reaction in which TPA units are replaced by DMT. The intrinsic viscosity of the polyesters herein is determined in 60/40 (wt/wt) phenol/tetrachloroethane at 25 ℃ at a concentration of 0.5g/dL and is reported as dL/g. The metal content of the material is determined by X-ray fluorescence in a manner similar to ASTM D6247-18 (modified for the sample matrix and analyte of interest). The use and amount of DMT added to the system did not negatively affect the IV build of the material.

TABLE 3

Sample (I)	DMT %	Ti (ppm)	Sb (ppm)	IV
					1	0	11.6	165	0.7
2	25	14.4	203	0.82
					3	50	12.4	194	0.81
4	75	13.8	202	0.76
					5	100	14.3	190	0.86

Standard solid stating procedures (24 hours at 220 ℃,1 mmHg) were performed to determine the effect DMT would have on IV boost. The results shown in table 4 indicate that the addition of DMT to the PTA-based process did not have a negative impact, as with the resin-based process. This result was unexpected in view of the poor reactivity of any residual methyl end groups in the solid stating. Without being bound by any theory, it is believed that the high temperature and long residence time in the first reactor may have reduced the methyl end group content to a point where it no longer prevents the build-up of solid state IV.

TABLE 4

Sample (I)	DMT %	IV (resin)	IV (solid state)
				6	0	0.629	1.605
7	50	0.66	1.482
				8	100	0.742	1.961

For the avoidance of doubt, it is expressly provided that information and descriptions herein regarding features or elements of one aspect of the disclosure may also be used and relied upon to support those features and elements as described with respect to other aspects of the disclosure.

The foregoing description of various embodiments of the disclosure has been presented for the purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure to the precise embodiments disclosed. Many modifications and variations are possible in light of the above teaching. The embodiments discussed were chosen and described to provide the best illustration of the principles of the disclosure and its practical application to thereby enable one of ordinary skill in the art to utilize the disclosure in various embodiments and with various modifications as are suited to the particular use contemplated. All such modifications and variations are within the scope of the disclosure as determined by the appended claims when interpreted in accordance with the breadth to which they are fairly, legally and equitably entitled.

Claims

1. A process for preparing a polyester having recycled content, the process comprising the steps of: feeding a recycle feed comprising an ester recycle material selected from the group consisting of r-DMT, transesterified r-DMT, and combinations thereof to at least one reaction zone to form a reaction mixture comprising recycled components in the at least one reaction zone; reacting the reaction mixture to form a polyester oligomer mixture having recycled content; and polycondensing the recycled component oligomer mixture to form a polyester with recycled components.

2. The process of claim 1, wherein the feeding step further comprises feeding a glycol recycle material selected from the group consisting of r-EG, r-DEG, and combinations thereof to at least one reaction zone.

3. The method of claim 1, wherein the recycle feed further comprises dimethyl isophthalate recycle material (r-DMI).

4. The method of claim 1, wherein the recycle feed further comprises residual catalyst material selected from germanium material and antimony material, and combinations thereof.

5. The method of claim 1, wherein the feeding step further comprises feeding a raw feed to at least one reaction zone, the raw feed comprising at least one raw glycol component.

6. The method of claim 5, wherein the primary feed is substantially free of primary diester components; or wherein the raw feed is substantially free of raw diacid components.

7. The method of claim 1, wherein the reacting step comprises reacting the reaction mixture at a temperature of at least 250 ℃ for a total average residence time of 30 minutes to 12 hours.

8. The method of claim 5, wherein the native feed further comprises a native diacid component.

9. The process of claim 8, wherein the primary diacid component is at least 90 mole percent terephthalic acid, based on the total diacid content of the primary feed.

10. The method of claim 9, wherein the native diacid component comprises one or both of terephthalic acid and isophthalic acid.

11. The method of claim 1, wherein the reacting step is carried out in the presence of a metal-based catalyst, wherein the metal of the metal-based catalyst is selected from the group consisting of Sb, Ti, Sn, Mo, Ge, Zn, Co, Mn, Cd, Al, Li, Pb, Mg, Ca, Ag, Na, Ce, Ba, Hg, Fe, Cu, and combinations thereof.

12. The method of claim 5, wherein the native glycol component of the native feed comprises ethylene glycol, 1, 3-propanediol, 1, 4-butanediol, 1, 5-pentanediol, 1, 6-hexanediol, 1, 7-heptanediol, 1, 8-octanediol, 1, 10-decanediol, diethylene glycol, triethylene glycol, polyethylene glycol, polytetrahydrofuran, polyoxymethylene, isosorbide, 1, 3-and 1, 4-Cyclohexanedimethanol (CHDM), 1, 4-cyclohexanedimethanol, 2,4, 4-tetraalkylcyclobutanediol, including 2,2,4, 4-Tetramethylcyclobutanediol (TMCD), neopentyl glycol, 2, 4-trimethyl-1, 3-pentanediol, glycerol, trimethylolpropane, pentaerythritol, 1, 4-trimethyl-1, 3-pentanediol, glycerol, trimethylolpropane, and mixtures thereof, One or more of resorcinol, hydroquinone and catechol, and isomers and combinations thereof.

13. The method of claim 5, wherein the glycol component of the virgin feed comprises one or more glycols selected from: ethylene glycol, diethylene glycol, neopentyl glycol, 2,4, 4-tetramethyl-1, 3-cyclobutanediol (TMCD), Cyclohexanedimethanol (CHDM), isomers thereof, and combinations thereof.

14. The process of claim 1, further comprising the step of depolymerizing waste polyester to form a depolymerized product comprising r-DMT prior to the feeding step; and wherein the depolymerisation step is carried out by methanolysis.

15. The process of claim 1 wherein said ester recycle material of said feeding step is fed in an amount sufficient to account for 1 to 100 mole percent based on the total moles of 1, 4-dicarboxybenzene equivalents of diacid in said polyester with recycled content.

16. The method of claim 5, wherein the step of feeding the native feed precedes the step of feeding the recycle feed; and wherein the process further comprises the step of reacting at least some of the virgin feed in the reactor to form virgin polyester oligomers prior to or simultaneously with the feeding step of the recycled feed.

17. The process of claim 1, further comprising, prior to the feeding step, the step of pre-reacting at least some of the r-DMT with one or more glycols selected from the group consisting of diethylene glycol, neopentyl glycol, 2,2,4, 4-tetramethyl-1, 3-cyclobutanediol, cyclohexanedimethanol, ethylene glycol, 2,2,4, 4-tetramethyl-1, 4-cyclobutanediol, and isomers and combinations thereof, to form a transesterified r-DMT.

18. The method of claim 18, wherein the pre-reaction step is conducted in the presence of a metal-based catalyst, wherein the metal of the metal-based catalyst is selected from the group consisting of Sb, Ti, Sn, Mo, Ge, Zn, Co, Mn, Cd, Al, Li, Pb, Mg, Ca, Ag, Na, Ce, Ba, Hg, Fe, Cu, and combinations thereof.

19. A recycle feed composition for use in the production of polyesters having recycled components, the recycle feed comprising:

an ester recycle material selected from the group consisting of r-DMT, transesterified r-DMT, and combinations thereof; and at least one of:

dimethyl isophthalate recycle material (r-DMI); and

a residual catalyst material selected from the group consisting of germanium materials and antimony materials and combinations thereof.

20. The recycle feed composition of claim 20, wherein the recycle feed composition comprises dimethyl isophthalate recycle material (r-DMI) in an amount of 3000 ppm or more; or wherein the residual catalyst material is present in an amount of 5 to 500 ppm based on parts of the feed composition.